WavepotWobble.js

/*!
 *
 * welcome to wavepot
 * ------------------
 *
 * this is a live editor. you create a function named `dsp`
 * that accepts the parameter `t`, the coefficient of time,
 * which you use to generate a single sample (range -1..1)
 *
 * below is the smallest example possible, a simple sine wave
 * generator. check out more complex demos on the right ---->
 *
 * have fun!
 *
 */
 
var tempo = 100;
var tempo_frequency = tempo / 60.0;
 

function dsp(t) {
  return 0.1 * OctaveBass(t, BassFrequency(t)) + 0.2 * Kick(t) + 0.3 * Chords(t);
  //return 0.2 * Kick(t);
}

var Sine = function(t, freq) {
  return Math.sin(2 * Math.PI * freq * t);
};

var Square = function(t, freq) {
  var sine_value = Sine(t, freq);
  if(sine_value < 0) {
    return -1;
  }
  else {
    return 1;
  }
};

var Triangle = function(t, freq) {
  var period = 1.0 / freq;
  var a = period / 2; 
  return 2 / a * (t - a * Math.floor(t / a + 0.5)) * Math.pow(-1, Math.floor(t / a - 0.5));
};

var Noise = function(t) {
  return Math.random();
}

var OctaveBass = function(t, freq) {
  return MixBass(FullBass(t, freq), EmptyBass(t, freq), t);
}

var FullBass = function(t, freq) {
  
  return ( 0.3 * Square(t, freq) + 0.3 * Square(t, freq + 1)  + 0.3 * Triangle(t, freq * 2) + 0.1 * Noise(t) );
};

var EmptyBass = function(t, freq) {
  return 0.9 * Square(t, freq) + 0.1 * Noise(t);
};

var MixBass = function(full, empty, t) {
  
  var ratio = -Sine(t, WobbleFrequency(t));
  
  return ratio * full + (1-ratio) * empty;
}

var ClampTimeToBeat = function(t) {
  return Math.floor(t * tempo_frequency);
};

var WobbleFrequency = function(t) {
  
  var freqs = [2, 2, 2, 1, 2, 2, 3, 4, 2, 2, 2, 1, 2, 2, 3, 1];
  
  var beat = ClampTimeToBeat(t) % freqs.length;
  
  return tempo_frequency * freqs[beat];
};

var BassFrequency = function(t) {
  
  var A = 55.0000;
  var F = 87.3071;
  var C = 65.4064;
  var Bb = 58.2705;
  var B = 61.7354;
  
  var freqs = [A, A, F, F, C, C, B, Bb];
  
  var beat = ClampTimeToBeat(t) % freqs.length;
  
  return freqs[beat];
};

var Kick = function(t) {
   var beat_location = (t * tempo_frequency) % 1;
   
   return Math.sin(2 * Math.PI * Math.sqrt(5000*beat_location));
}

var Chords = function(t) {
  var eight_location = (2 * t *tempo_frequency) % 1;
  
  var G4 = 391.995;
  var A4 = 440;
  var B4 = 493.883;
  var Bb4 = 466.164;
  var C5 = 523.251;
  var D5 = 587.330;
  var E5 = 659.255;
  
  var chords = [
    [A4, C5, E5],
    [],
    [A4, C5, E5],
    [],
    [G4, D5, E5],
    [],
    [G4, B4, D5],
    [G4, Bb4, D5]
  ];
  
  var beat = ClampTimeToBeat(t);
  
  var chord_to_use = chords[ (beat) % chords.length ];
  
  var waveform = 0;
  for(var i = 0; i < chord_to_use.length; i++) {
    waveform += ChordNote(t, chord_to_use[i]);
  }
  
  return waveform / Math.max(chord_to_use.length, 1);
  
}

var ChordNote = function(t, freq) {
  var beat_location = (t * tempo_frequency) % 1;
  var waveform = Sine(t, freq) + Sine(t, freq * 1.01); 
  return waveform * Math.exp(-beat_location / 0.75);
}